2) In my case, I would install the CPU LCS as it already is, exhausting air out the back of the case. I would then install the GPU LCS to intake air through the bottom of the case, through a dust filter, of course. Alternatively, I could remove the case's front intake fan, and use the GPU LCS to either intake or exhaust in it's place, keeping an eye out for positive pressure.

Then again, I have a case that was designed around a plethora of cooling solutions, so depending on your case, YMMV.